Various jurisdictions have regulations which require certain components within a fueling environment (such as a fueling forecourt) to keep complete logs of pertinent data for auditing by the appropriate authority. Examples of components for which logs may be required include site automation systems, point-of-sale (POS) systems, and fuel dispenser control systems. The logs may keep track of configuration changes, times at which the system was accessed, sensor readings, times of last calibration, and price changes, among others. Notably, it is also necessary to keep highly accurate records of the time at which each log entry occurred.
However, accurate timekeeping is difficult for a variety of reasons. Currently, for example, components for which logs are required keep time using a real-time clock (RTC). RTCs are typically in the form of an integrated circuit and include an independent power source, such as a battery, so that RTCs can keep the time even while a component is turned off. Time is kept at the component by the operating system (OS) or real-time OS (RTOS) of the component periodically reading from the RTC using interrupt service routines. Unfortunately, however, RTCs are prone to drift over time. Moreover, the time kept by the component's OS or RTOS may also drift away from the time kept by the RTC during intervals between readings from the RTC. This causes complex algorithms to attempt to refresh the OS or RTOS time by reading from the RTC more frequently, which can be time consuming and inefficient.
Clocks which can synchronize themselves using radio transmissions (“radio clocks” or “radio-controlled clocks”) are also known. In particular, certain radio transmitters may transmit signals modulated with a time code which identifies the current time (e.g., year, month, day, hour, minute, seconds, etc.) in a particular jurisdiction or in Coordinated Universal Time (UTC). One example of such a radio transmitter is the WWVB National Institute of Standards and Technology radio station near Fort Collins, Colo. The radio transmitters themselves may obtain the current time from a time standard, such as an atomic clock. A radio clock tuned to the frequency of the transmitter receives and decodes the time code modulated onto the carrier wave of the radio transmitter. Accordingly, the radio clock can thereby set or update its clock with the current time. Where the time code is in UTC, the radio clock is programmed to apply time zone and daylight savings time offsets, as applicable, for a particular jurisdiction. In general, radio clocks can obtain accuracy at least within a hundredth of a second relative to the time standard.
Satellite navigation receivers which communicate with Global Navigation Satellite Systems (GNSS) are also known. These receivers include antennas which receive signals from GNSS satellites which enable the receivers to obtain accurate information regarding the current time and the location of the receiver. Examples of GNSS include the United States' Global Positioning System (GPS), Russia's GLONASS, and Europe's GALILEO. Other GNSS are currently being developed by India, China, and Japan. Time information obtained by satellite navigation receivers is very accurate, in some cases within 100 nanoseconds of the atomic clocks carried by the satellites.